Point detonating fuze for high velocity round



Sept. 9, 1958 A. E. STEVENSON ETAL 2,850,930

POINT DETONATING FUZE FOR HIGH VELOCITY ROUND Filed July 8, 1955 v #VVENTOES m Alheri 13511515115011 5w FELTKE'H.T1'LEIITL 5011 P 244. By

fiffflwalfloeow ATTORNEYS section 7. two part body a longitudinal axis X-X of rotation of the fuze. bore or recess 14 is formed in the surface of the rotor Unite atent POINT DETONATING FUZE FOR HIGH VELOCITY ROUND Albert E. Stevenson, Kirkwood, and Parke H. Thompson, Glendale, Mo., assignors to the United States of America as represented by the Secretary of the Army Application July 8, 1955, Serial No. 520,941

7 Claims. (Cl. 102--79) This invention relates ot point detonating fuzes for spin-type projectiles.

An object of the invention is to provide a fuze of sturdy construction which will not wipe off the projectile or be deformed on impact with a target.

Another object of the invention is to provide a fuze having its vital elements deeply housed within the intruding portion of a sturdy fuze body to prevent deformation of the vital elements.

Another object of the invention is to provide a fuze which will penetrate heavy aluminum aircraft construction and burst within the target aircraft without undue deformation.

Another object of the invention is to provide a fuze which is sensitive to impact with the thinnest aircraft skin or other relatively fragile construction.

A further object of the invention is to provide a ruze having a firing pin which floats freely during flight and has no resistance other than friction to overcome on impact with a target.

A still further object of the invention is to provide a fuze of simple construction without small complicated parts such as springs, detents or the like.

p Other objects and advantages will be apparent from the following detailed description and the accompanying drawings, in which:

Fig. 1 is a longitudinal sectional view of a fuze show- 1 ing one form'of the invention,

Fig. 2 is a detail plan view of aform of spring shown in Fig. 1, a

Fig. 3 is a longitudinal sectional view of a fuze show- ;ing a modified form of the invention.

. Fig. 4 is a detail plan view of a form of spring shown in Fig. 3,

Fig. 5 is a detail view of a buffer element shown in Fig. 3,

Fig. 6 is a rear end view of the buffer element, and

Fig. 7 isa longitudinal sectional view of a fuze showing a. further modified form of the invention.

Referring now to Figure l of the drawings, 5 indicates a fuze body comprising a main section 6 and front section 7.. The front section is insertable part Way as shown into. coaxial bores and 10a in the main section and is secured thereto by means of a peripheral flange 8 extending forwardly from the main section, and being rolled to impinge on a frusto-conical face 9 on the front Bore 10 forms a recess interiorly of the symmetrically disposed about a longitudinal axis of rotation indicated at X-X. Rotatable in the recess under the influence of centrifugal force during flight is a ball rotor 11 having a diametrical bore 12 extending therethrough. A primer 13 is fixed in the bore 12 and in normal safe position of the fuze the rotor is positioned with the primer out of alignment with the A small which is aligned with axis XX when the rotor is in safe position.

Slidable in a bore 15 in the front section' 1 7, coaxial with the longitudinal axis of rotation X- -X and with the small bore 14 is a firing pin 16 normally inserted into the bore 14 to hold the rotor in the safe position shown upon the drawing. Near its front end a peripheral groove 17 is formed in the firing pin and forwardly of the groove the firing pin has a diametrically enlarged head 18 forming front and rear shoulders 19 and 20 respectively for a purpose to be presently set forth. The forward end of the front section 7 of the fuze body is diametrically reduced in successively smaller annular step-like formations to form an armor piercing nose 21 and rearwardly thereof and adjacent thereto a peripheral head 22 is formed.

A unitary spring structure 23, Fig. 2 is assembled with the front section 7 of the fuze body by means of an integral attaching flange 24 secured to and about the peripheral bead 22 as by crimping or rolling. The web portion of the spring structure is cut radially, as at 25, to form spring fingers 26 shown as six in number and pierced centrally at 27 so that in the assembled position the radially inward ends of these fingers engage in the groove 17 in the firing pin. Chordal portions of the web are removed, as at 28, so that each spring finger is attached to the continuous circumferential band of the spring by an intermediate section 29 having a width equal to the separation between consecutive cut-outs 28 and which define pivot axes about which the respective fingers will pivot under centrifugal force developed by spin about axis XX.

The primer 13 is loaded with any desired time-delay composition, such as black powder, to retard passage of fire to an explosive lead 30 and a booster (not shown), until the fuze and its projectile are within the target, A nose cap 31 is secured to the main body section 6 by any preferred means such as shown at 32, and is thin enough to effect detonation of the fuze on impact with the thinnest aircraft construction. When assembled with the fuze body, the spring fingers 26 are stressed forwardly by the front formation of section 7 to develop suflicien't bias, therein to hold the firing pin in engagement with the rotor that is, with its point within bore 14, to hold the rotor against accidental displacement and to advance the mass center of each spring finger forwardly of the peripheral bead 22 or, what is practically the same thing, the pivot axes defined by sections 29. Under the centrifugal forces developed by the high speed of rotation in flight the spring fingers 26 flex outwardly about their sections or axes 29 and bear against the front shoulder 19 on the enlarged head 18 of the firing pin and on continued movement withdraw the pin from the bore 14 in the rotor. Under continued rotation the inner ends of the spring fingers snap over the enlarged head 18 of the firing pin to the dotted position in Fig. 1 and release the pin. The rotor being thus freed, moves to align the primer with the pin. On impact with a target the nose cap 31 is deformed and the firing pin is forced into the primer thus initiating the fuze.

A slightly modified form of the invention is disclosed in Figures 3 through 6. Referring to Fig. 3, the reference numeral 5 identifies a construction wherein a main section 6' and a rear section 35 constitute a two-piece body threadedly united at 35' and conjointly forming a two-piece body spherical recess 10 to house a ball rotor 11 with a smooth fit. The rotor 11 may be a duplicate of the one previously described in connection with Fig. 1. A firing pin 16' slides in a bore 15' axially disposed in the main section 6 and has formed thereon a diametrically enlarged head 18 forming a forward shoulder 19; and an annular groove 17' providing a rear shoulder 20'. A forwardly projecting screw-threaded stud 36 integral with the pin, supports a buffer structure 37 The forward face of the main section 6' has a frusto-conical formation 38 for a purpose to be presently disclosed. A peripheral bead 22, similar to the bead 22 shown in Figure l, is formed on the main section 6 at the base of the frusto-conical formation.

A unitary spring structure 23, Fig. 4, somewhat similar to the spring structure of Figure 1 is employed in this form of the invention and is assembled with the main section 6' of thefuze body by means of an integral attaching flange 24' secured as by crimping or spinning, to the peripheral bead 22'. The web portion of the spring structure is centrally pierced as at 2'7 to engage the groove 17 on the firing pin and is further stamped out to form radial fingers 26 having integral right angularly bent extensions 39 to advance the mass center of each spring finger a substantial distance forwardly of the peripheral bead 22,. When assembled with the fuze body the spring fingers are stressed forwardly by the frustoconical face 38 to develop sufficient bias therein to hold the firing pin in the bore 14 of the rotor against accidental displacement by contact with the shoulder 20'. Under rotation the fingers bend, about chordal axis indicated at 29 and bear against the front shoulder 19 on the firing pin and withdraw the pin from the recess 14 in the rotor. The buffer structure 37 is employed when it is desired to make the fuze sensitive to light impact which would produce slight deformation only of nose cap 31' secured at 32 to the main body section 6. The buffer structure 37 is formed with depressions 40 providing passageways for the spring fingers during outward movement thereof, the remaining portionsthereof forming webs 41 which are assembled to lie in radial planes midway between the spring fingers 26'. When assembled the angularly bent extensions 39 extend forwardly within the depressions 40 and retain the alternate spacing of the spring fingers 26' and the webs 41 so that the spring fingers can move outwardly under rotation through the depressions 40 after snapping past the enlarged head 18 on the firing pin.

A further modified form of the invention is disclosed in Figure 7. The fuze body 5a is similar to the one disclosed in Figure 3 and comprises a main section 6a and a rear section 35a. A spherical recess 10 is formed conjointly by cavities in parts 6a and 35a interiorly of the two-piece body to house a ball rotor 11, which may be identical with those shown in Figs. 1 and 3. A firing pin 16a slides in a bore a coaxial with the axis XX of rotation of the fuze and has a diametrically enlarged head 18a at its forward end forming a forward shoulder 19a and an annular groove 17a forming a rear shoulder 20a. At its forward end the firing pin is elongated to provide a plunger 45 which is slidably supported in a bore 46 in a guide member 47 secured in the forward end of a nose cap 31a. main section 6a as at 32a.

The nose cap is secured to the The forward face of the main section 6a has a frusto-conical formation 38a similar to the formation 38 of Figure 3. A peripheral bead 22a is formed on the main section 6:: at the base of the frusto-conical formation 38a. A unitary spring structure 23a similar to the spring structure employed in the modification disclosed in Figure 3 is assembled with the main section 6a by means of an integral attaching flange 24a secured to the peripheral bead 22a as by crimping, rolling or spinning.

When assembled with the fuze body the spring fingers 26a are stressed forwardly by the frusto-conical face 38:: to develop suflicient bias therein to hold the firing pin 16a in the bore 14 of the rotor against accidental displacement by contact with the shoulder 20a. The fingers flex outwardly under rotation and bear against the front shoulder 19a on the firing pin and withdraw the pin from the recess 14 in the rotor. The spring fingers 26a are formed with right angularly bent extensions 39a similar to, and for the same purpose as those shown in Figure 3.

It is believed that the construction and operat1on of the invention has been clearly presented and that further description is unnecessary since the functioning of the modification is the same as "in those previously described.

While we have disclosed three forms of the invention as presently known to us, various changes and modifications will occur to those skilled in the art after a study of the present disclosure. Hence the disclosure is to be taken in an illustrative rather than a limiting sense; and it is our desire and intention to reserve all modifications falling within the scope of the subjoined claims.

Having now fully disclosed the invention, what we claim and desire to secure by Letters Patent is:

l. A fuze for a spin-type projectile comprising a fuze body having a longitudinal axis of rotation, a peripheral head in said body concentric with the longitudinal axis and a recess symmetrically formed about the axis; a centrifugally operated rotor in said recess having a primer therein angularly displaced from the longitudi-nalaxis of rotation and a bore coaxial therewith in safe position; a firing pin slidable in said body and coaxial therewith and engageable at its rear end in the coaxial bore in said rotor to secure said rotor in safe position said pinhaving a peripheral groove near its forward end and a unitary spring structure having a peripheral attaching flange engaging said peripheral bead and having a series of radial flat spring fingers converging inwardly to engage the annular groove in said pin to hold said pin in the coaxial bore; said spring fingers bending outwardly under the influence of centrifugal force to withdraw said pin from the coaxial bore in said rotor and release said rotor to align its primer with said pin during flight of the projectile.

2. A fuze for a spin-type projectile comprising a fuze body having a longitudinal axis of rotation; a peripheral bead in said body concentric with the longitudinal axis and a recess symmetrically formed about the axis; a centrifugally operated rotor in said recess having a primer therein angularly displaced from the longitudinal axis of rotation and a bore coaxial therewith when in safe position; a coaxial firing pin slidable in said body and engageable at its rear end in the coaxial bore to secured said rotor in safe position and having an annular groove in its forward end forming a shoulder; a spring structure having a peripheral attaching flange engaging said peripheral bead and having a series of radial flat spring fingers converging inwardly to engage the annular groove in said I pin, said spring fingers being stressed forwardly when in assembled relation to exert rearward bias upon the firing pin, the mass center of each spring finger being disposed forwardly of said peripheral bead whereby said spring fingers are flexed outwardly under rotation to urge said firing pin forward and release said rotor and move said pin to armed position; and a nose cap Iimiting forward creep of said firing pin. Y

3. A fuze for a spin-type projectile comprising a fuze body having a forwardly extending substantially frustoconical armor piercing nose and a longitudinal axis of retation; a peripheral bead in said body concentric with the longitudinal axis and adjacent the base of said frustoconical armor piercing nose said body having a recess symmetrically formed about the axis; a centrifugally operated rotor in said recess having a primer therein angularly displaced from the longitudinal axis of rotation and a bore coaxial therewith when in safe position; a coaxial firing pin slidable in said body and engageable at its rear end in the coaxial bore to secure said rotor in safe position and having an annular groove in its forward end forming a shoulder; a unitary spring structure having a peripheral attaching flange engaging said peripheral bead and having a series of radial flat spring fingers convering inwardly to engage-the annular groove in said pin, said spring fingers being stressed forwardly by said frustoconical armor piercing nose when in assembled relation to exertrearward bias upon the firing pin and to advance the mass center-of each spring finger forwardly of said pcripheral bead whereby said spring fingers are flexed outwardly under rotation to-force said firing pin forwardly out of engagement with the coaxial bore in said rotor to slide freely in said fuze body; and a nose cap secured to the forward end of said body limiting forward creep of said firing pin.

4. A fuze for a spin-type projectile comprising a fuze body having a longitudinal axis of rotation; a peripheral bead in said body concentric with the longitudinal axis and a recess symmetrically formed about the axis; a centrifugally operated rotor in said recess having a primer therein angularly displaced from the longitudinal axis of rotation and a bore coaxial therewith when in safe position; a coaxial firing pin slidable in said body engageable at its rear end in the coaxial bore to secure said rotor in safe position and having an annular groove and a diametrically enlarged head at its forward end; a spring structure having a peripheral attaching flange engaging said circular bead and having a series of radial spring fingers converging inwardly to engage the annular groove in said pin, said spring fingers being stressed forwardly when in assembled relation to exert rearward bias upon the firing pin, each spring finger being formed with an angular flange extending forwardly therefrom to advance the mass center of said spring fingers forwardly of said peripheral bead whereby said spring fingers are flexed outwardly under rotation to release said firing pin from said roto; a forwardly extending nose cap secured to the forward end of said body; and a buffer element secured to said firing pin and extending forward into said nose cap to limit the forward movement of said pin and lessen the elapsed time between impact and detonation against a frail target, said buffer element having a depression formed therein in the path of outward movement of each said spring finger and its angular flange when said spring has flexed beyond said enlarged bead.

5. A fuze for a spin-types projectile comprising a fuze body having a longitudinal axis of rotation; a peripheral bead in said body concentric with the longitudinal axis and a recess symmetrically formed about the axis; a centrifugally operated rotor in said recess having a primer therein angularly displaced from the longitudinal axis of rotation and a bore coaxial therewith when in safe position; a coaxial firing pin slidable in said body and en- I gageable at its rear end in the coaxial bore to secure said rotor in safe position and formed at its forward end to provide an annular groove and a diametrically enlarged portion adjacent to and forwardly of the groove, said pin having a forwardly extending plunger; a spring structure having a peripheral attaching flange engaging said peripheral bead and having a series of radial spring fingers converging inwardly to engage the annular groove in said pin and the rearward face of said diametrically enlarged portion, said spring fingers being stressed forwardly when in assembled relation to exert rearward bias upon the firing pin, each spring finger being formed with an angular flange extending forwardly therefrom to advance the mass center of said spring fingers forwardly of said peripheral bead whereby said spring fingers are flexed outwardly under rotation to engage the diametrically enlarged portion of said pin, releasing said pin from said rotor and moving said pin forwardly into arming position; and a nose cap secured to the forward end of said fuze body and having an axially disposed hollow guide member fixed in its forward end to slidably receive said forwardly extending plunger, said axially disposed member having its rear end axially spaced from the forward face of said diametrically enlarged portion of said pin to limit forward creep of said firing pin.

6. In a centrifugally operated fuze, a fuze body having a longitudinal axis of rotation and a forwardly projecting surface of revolution about said axis, a firing pin slidable in an axial bore in said fuze body from a rearward safe position to a forward armed position, said pin having a rearwardly-facing abutment forwardly of said surface, and a leaf-type spring secured at its radially outward end adjacent the periphery of said surface of revolution and including at least one inwardlyand forwardlyprotruding finger extending beneath and rearwardly of said abutment, under stress imparted thereto by said forwardly projecting surface of revolution whereby said finger normally engages and urges said firing pin rearwardly and thereafter is flexed outwardly in response to centrifugal force to move said pin forwardly, arming means in said body normally held in safe position by said pin and released by forward movement of said pin under outward fiexure of said spring, and said spring comprising a generally circular sheet of flat resilient material having a continuous rim, said sheet having equiangularly-spaced radial slits from said rim to a central aperture whereby to define a plurality of radially-extending resilient fingers initially lying in the same plane and stressed forwardly by said surface of revolution during assembly and moveable farther forwardly and outwardly under the influence of centrifugal force.

7. In a point detonating fuze for a spin type projectile, a fuze body, a firing pin slidably mounted in said body and having a forward abutment surface and an adjacent rearward abutment surface thereon, a centrifugally operated arming means having a primer therein positioned out of alignment with said pin in unarmed position, interengaging means in said arming meas and said pin'to normally secure said arming means against movement, a centrifugally operated spring means mounted on said body with the inner end thereof normally positioned between said forward and said rearward abutment surfaces and cooperating with said rearward surface to positively hold said pin in interengagement with said arming means to retain said pin in a rearward unarmed position, said spring means moveable forwardly in response to spin and cooperating with said forward abutment surfaces to move said pin forwardly to an unarmed position thereby releasing said arming means for movement to an unarmed position in response to spin to align said primer with said pin, and said spring means including a spring which is pre-.

stressed forwardly to provide a rearward holding force to said pin in said unarmed position and moveable, in response to spin, outwardly from between said forward and said rearward abutment surfaces to provide an unobstructed path between said pin and said primer in armed position.

References Cited in the file of this patent UNITED STATES PATENTS 2,014,393 Mathsen Sept. 17, 1935 2,380,764 Junghans July 31, 1945 2,427,671 Graumann Sept. 23, 1947 2,450,899 Liljegren Oct. 12, 1948 2,495,432 Thompson Ian. 24, 1950 2,641,186 Apotheloz June 9, 1953 

